(CNN) -- The sequencing of the human genome is a scientific milestone, U.S. and British researchers said Monday, but the most important work lies ahead, in determining how to put the information to medical use.

The heads of the public and private efforts to decipher the genetic makeup of human beings announced the completion of a rough draft of the project -- more than 10 years after it was begun.

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Listen to President Clinton discuss the benefits of the Human Genome Project

"Mapping the human genome has been compared with putting a man on the moon, but I believe it is more than that," said Dr. Michael Dexter, the director of the Wellcome Trust, which funded the British part of the Human Genome Project.

"This is the outstanding achievement not only of our lifetime but perhaps in the history of mankind," Dexter told a London news conference.

The progress the researchers have made heralds a new era of medical discovery, U.S. President Bill Clinton and British Prime Minister Tony Blair declared at a White House news conference acknowledging the successes.

"This is the most important, most wondrous map ever produced by humankind," Clinton said in Washington. "Humankind is on the verge of gaining immense new power to heal. Genome science ... will revolutionize the diagnosis, prevention and treatment of most, if not all, human diseases."

Joining Clinton via satellite link from London, Blair called the genome project "the first great technological triumph of the 21st century."

Both leaders, however, emphasized the need to use the information wisely and maintain international cooperation in its development.

The medical benefits of genome science, they agreed, must be used to benefit all people, not only a privileged few. Individual privacy must be protected as science moves forward with the project, and the information must not be used to discriminate against any group or person.

If the project proves anything, Clinton said, it is that "the most important fact of life on this Earth is our common humanity."

The sentiment was echoed by the men who have directed the U.S. research teams pursuing the genome puzzle.

"What a profound responsibility it is to do this work," said Dr. Francis Collins, director of the Human Genome Project at the National Institutes of Health. "Historians will consider this a turning point."

"It is my belief that the basic knowledge that we're providing to the world will have a profound impact on the human condition and the treatments for disease and our view of our place on the biological continuum," Venter said.

All the researchers involved praised the high level of international cooperation that enabled them to reach this stage, and they pledged to keep that momentum going.

Mapping the chemical sequences for human DNA -- the chemical "letters" that make up the recipe of human life -- is a breakthrough that is expected to revolutionize the practice of medicine by paving the way for new drugs and medical therapies.

Specific sequences of DNA characters form the genes that make us what we are, govern our biological functions and determine our susceptibility to illnesses like cancer or diabetes.

In the sequencing phase, researchers identified the approximately 3.5 billion chemical letters (A, C, G, T) that make up human DNA, the building block of the genes.

In the assembling phase, they put those letters in the correct order, allowing them to "read" each gene.

Venter said Celera had sequenced 99 percent of the human genome and had assembled 3.21 billion letters of genetic code. The most difficult part is yet to come, however.

In the final step, annotating, scientists must identify each gene and its function. They will look for the genetic variations in people -- variations that could be the cause of countless diseases.

That step is expected to take several years to complete. However, scientists said doctors one day would be able to study a person's genetic profile, determine his susceptibility to various diseases, and design a course of treatment to prevent illness.

"You're going to see a proliferation of discoveries about the genetic contributions to diabetes and heart disease and high blood pressure and schizophrenia and multiple sclerosis and on down the list," Collins told CNN.

"Conditions that we know have genetic contributions but which have been rather difficult to nail down, this set of power tools that the genome project is producing will accelerate this discovery process rather dramatically, and we're going to see the consequences of that in the next three to five years," Collins said.

Despite the potential for medical advancements, many Americans are divided over the implications of the genome project.

In a CNN-Time magazine poll taken two weeks ago, 46 percent of respondents said they expected harmful results from the endeavor. Forty percent expected benefits. About 41 percent of respondents said the project is morally wrong; 47 percent disagreed.

Venter

Nevertheless, a majority of respondents -- 61 percent -- said they would want to know if they were predisposed to developing a genetic disease. About 35 percent would not want to know.

The question of who should have access to genetic information is one of the most controversial stemming from the project.

In the poll, 67 percent of respondents said doctors should be able to get genetic information. About 20 percent said it should be available to insurance companies, and only 14 percent said it should be available to the government.

Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania, said providing genetic information to insurers or employers could have negative consequences if a person is predisposed to a particular disease.

"They might say, 'We don't want to hire you if you're going to have high medical costs. We don't want to give you life insurance,'" Caplan said.

Collins

Protecting the privacy of genetic information is extremely important, Caplan added, as is the issue of consent. "We need to have a law, a federal law -- probably an international law -- that says no testing without the express permission of the person," Caplan said.

The Human Genome Project is an international consortium supported mostly by the U.S. National Institutes of Health and the Wellcome Trust, a philanthropic organization based in London. Celera Genomics is a private company in Rockville, Maryland.

The high level of international cooperation was instrumental in accomplishing so much of the project so quickly, the NIH's Collins said Monday.

Although the public and private groups are using different methods in their human genome projects, they both have as a goal the discovery of the chemicals of the approximately 80,000 genes that make up the human body.